Move symbols to the top container; update images

Use SVG images from Upstatement.

[#44616163]
Update ke image; make transparent, solid on hover

Original KE image from Upstatement had colors reversed, and had
no background which made reading text hard.

Both icons are now generally transparent, and become opaque on
mouse hover.

It would be good to also have a hover tooltip. We don't have a
good pattern for this right now (no native solution in SVG, unlike
alt-text in html), but could easily make one.

[#44616163]